7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Laser ablation plasma and its application for elemental analysis

Cong Li1,*, Huace Wu1, Zhenhua Hu2, Longfei Li1, Zhonglin He1, Ran Hai1, Ding Wu1, Fang Ding2,Rui Ding2, Liang Wang2, Jiansheng Hu2, Junlin Chen2, Guang-nan Luo2, Hongbin Ding1,**
1
Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry ofEducation), School of Physics, Dalian University of Technology, Dalian, P.R. China.
2
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, P.R. China*e-mail (Cong Li): cli@dlut.edu.cn **e-mail (Hongbin Ding): hding@dlut.edu.cn

The Laser Ablation Plasma (LAP) is generated bylaser-matter interaction when the laser power density
exceeds the ablation threshold of material. The emission
spectra of laser ablation plasma have attracted greatinterest in the scientific community because they allow
the study of fundamental aspects such as
spatial-temporal evolution of laser ablation plasma, andvarious applications in many different fields of sciencesuch as VUV light source, elemental analysis on the firstwall in fusion devices. The online elemental analysis on
the plasma-facing components (PFCs) is a crucial issue
for magnetic confinement nuclear fusion deceives, suchas tokamak and stellarator. Elemental distribution
directly reflects the conditions of PFCs and processes ofplasma-wall interaction (PWI). The laser-induced
breakdown spectroscopy (LIBS) diagnostic technology
provides a promising method for wall composition
monitoring for nuclear fusion deceives. In recent years,
we have developed LIBS for characterization of theco-deposition of impurities, fuel retention, wallconditioning on the first wall in EAST and HL-2A/M
tokamaks as well as W7-X stellarator. [1,2] An in situ
LIBS system in EAST has been built up to provide
elemental composition on the first wall since 2014. [3]Recently, an in situ endoscopic laser-induced
breakdown spectroscopy diagnostic system (figure 1) for

the full tungsten metal upper divertor in EAST has beendeveloped since 2021 experimental campaign. Thispresents an online elemental distribution on the divertor
with various discharge parameters and wall conditions.
The results show that the elemental distribution on the W
divertor tiles is nonuniform. The fuel ratios (D/(D+H)) in
inner target are about 90% which is higher than the ratios
in the dome region. The dynamic D content on W
divertor decreases after the plasma exposure due to thedominant short retention with outgassing process. The
observable high contents of Li and other impurities suchas Mo, Cu, etc. are measured on dome region which iscorresponding to a deposition-dominated region during
the discharges. Both D retention rate and Li deposition
rate are higher near the inner target. These works also
provide the key technology of wall elemental diagnosis
for the future fusion devices. Further details will bepresented at the conference.
References[1] C. Li, …H. Ding*, Front. Phys. 11, 114214 (2016).
[2] C. Li, …H. Ding*, Spectrochimica Acta Part B, 160,105689 (2019).
[3] D. Zhao, C. Li, …H. Ding*, Rev. Sci. Instrum. 89,073501 (2018).

Figure 1 In situ endoscopic laser-induced breakdown spectroscopy diagnostic system in EAST